Characteristic Analysis And Optimization Of Piston Compressor Crankshaft

As the key parts of the compressor,the crankshaft bears complex external load with periodic variation,which may lead to violent vibration and makes the compressor produce excessive noise.In particular,when the stiffness of the crankshaft is not enough,the torsional vibration will become the main failure form of the crankshaft.Therefore,the design of the crankshaft can directly affect the performance and reliability of the compressor.In the traditional design method,there is a lack of in-depth study on the torsional vibration of the crankshaft.The traditional design cannot meet the needs of modern product design to some extent.However,the experimental design method and multi-objective optimization design method can effectively overcome the shortcomings of the traditional design with a significance in terms of improving the dynamic characteristics of the crankshaft,increasing the overall efficiency and reducing the problems of vibration and noise.In this thesis,the dynamic characteristics of crankshaft were optimized based on multi-body dynamics method and experimental design method.A small piston-type refrigeration compressor was taken as the research object.According to the working principle of the piston-type refrigeration compressor,CAD software was adopted to establish the three-dimensional model of the crankshaft system and ADAMS software was used to conduct multi-body dynamics analysis to get the stress distribution in the condition of the maximum shaft power and the changes of the torsional vibration amplitude,which provided the necessary data for subsequent optimization.In addition,optimization design method was borrowed to study the influence of multiple design variables on the torsional angle displacement,strength and quality of crankshaft.Through the orthogonal test,the three kinds of design variables which had significant impact on the torsion angle displacement,strength and quality of the crankshaft(the balance of the transition fillet radius,the center position of the small end of the balance weight and the thickness of the crank)were analyzed.Based on the two-order response surface method,the expression of the relationship between the screening parameters and the torsion angle displacement,strength and mass was constructed.The genetic algorithm(NSGA-II)was used to optimize the parameters.The optimization results showed that the curve decreased11.31%,22.88%,and 25.10% respectively in terms of the three optimization objectives of the crankshaft,namely the weight,the maximum torsion angle of the free end and the peak stress of the crankshaft.The results of this study showed that,the proposed method on the basis of the multi-body dynamics,the experimental design and the multi-objective optimization were effective in reducing the torsional vibration of the crankshaft and the anticipated effect was reached.The results provided a reference for the study of the lightweight and stiffness of crankshaft and the ability of resisting the torsional vibration.